Formoterol

• Asthma Maintenance (with ICS)
• COPD Treatment
• Exercise-Induced Bronchospasm Prevention
• Chronic Bronchitis

Formoterol is a long-acting beta-2 adrenergic agonist (LABA) bronchodilator used in the maintenance treatment of asthma and chronic obstructive pulmonary disease (COPD). This medication provides rapid-onset, long-duration bronchodilation and is used in combination with inhaled corticosteroids for asthma management.

Mechanism of Action

Formoterol is a selective beta-2 adrenergic receptor agonist that binds to beta-2 receptors on airway smooth muscle cells. This binding activates adenylate cyclase, increasing intracellular cyclic AMP (cAMP) levels, which leads to relaxation of bronchial smooth muscle and bronchodilation. Formoterol has a unique pharmacological profile: it has rapid onset of action (within 1-3 minutes) similar to short-acting beta-agonists, yet also has a long duration of action (12 hours) characteristic of LABAs. This is due to its moderate lipophilicity, allowing both direct receptor binding and membrane partitioning with gradual release.

Available Formulations

Formoterol fumarate is available as a dry powder for inhalation in single-dose capsules (12 mcg) used with a specific inhaler device, and as a solution for nebulization. It is also available in fixed-dose combination inhalers with budesonide (for asthma and COPD), with mometasone (for asthma), and with aclidinium (for COPD). The formulation dictates the specific inhalation device used.

Medical Uses

Formoterol is FDA-approved for maintenance treatment of asthma in patients 5 years and older (only in combination with an inhaled corticosteroid), maintenance treatment of bronchoconstriction in COPD including chronic bronchitis and emphysema, and prevention of exercise-induced bronchospasm in patients 5 years and older. For asthma, LABAs should only be used in combination with an inhaled corticosteroid—never as monotherapy.

Dosing Guidelines

For asthma maintenance (with ICS), typical dosing is 12 mcg twice daily via DPI. For COPD maintenance, 12 mcg twice daily is standard. For prevention of exercise-induced bronchospasm, 12 mcg 15 minutes before exercise; additional doses should not be used for 12 hours. Maximum recommended dose is 24 mcg twice daily for asthma/COPD. When using fixed-dose combinations, follow the specific product labeling. Formoterol should not be used for acute symptom relief.

Important Safety Information

Formoterol carries a boxed warning stating that LABAs increase the risk of asthma-related death and should only be used for asthma in combination with an inhaled corticosteroid. Once asthma is well-controlled, step down therapy if possible. LABAs should not be used for acute symptoms; a rescue inhaler (SABA) should be available. Paradoxical bronchospasm may occur. Cardiovascular effects (tachycardia, hypertension, arrhythmias) may occur, particularly at higher doses. Hypokalemia and hyperglycemia are possible.

Drug Interactions

Beta-blockers may diminish the bronchodilatory effects of formoterol; selective beta-1 blockers may be used with caution when necessary. MAO inhibitors and tricyclic antidepressants may potentiate cardiovascular effects. QT-prolonging medications may increase the risk of arrhythmias. Diuretics may potentiate hypokalemia. Xanthine derivatives (theophylline), steroids, and other sympathomimetics may potentiate adverse effects.

Special Populations

There are no adequate studies in pregnant women. Beta-agonists may interfere with uterine contractility during labor. Use during pregnancy only if clearly needed. Formoterol is excreted in rat milk; caution is advised during breastfeeding. Safety and efficacy have been established in pediatric patients 5 years and older for asthma. Elderly patients may be more sensitive to cardiovascular effects; no specific dose adjustment is recommended. No dose adjustment is needed for renal or hepatic impairment based on available data, though caution is advised in severe disease.